Wall painting in Bunge church, Gotland, ca. 1405, one of the few contemporary representations of the Victual Brothers; significantly, the clothing and weaponry to identify the pirates is Gothic.[citation needed]

While Queen Margaret and Albert of Mecklenburg were battling for Scandinavian supremacy and Margaret's forces were besieging Stockholm, privateers named the Victual Brothers engaged in war at sea and shipped food to keep the city supplied. The name Victual Brothers is derived from the Latin word "victualia" — meaning provisions — and refers to their first mission, which was to supply food to the besieged city of Stockholm.

The Victual Brothers were organised as a brotherhood or guild, and attracted men from all over Europe[citation needed]. Their main naval enemy in 1392 was the powerful Hanseatic town of Lübeck, which supported Denmark in the war. Apart from Lübeck, the Hanseatic League initially supported the Victual Brothers. Most of the Hanseatic towns had no desire for a victory for Denmark, with its strategic location for control of the seaways.

At the climax of their power, the Victual Brothers occupied Gotland in 1394 and set up their headquarters in Visby. Maritime trade in the Baltic Sea virtually collapsed, and the herring industry suffered from their depredations. Queen Margaret even turned to King Richard II of England and sought to charter English ships to combat the pirates.

From 1395 onwards, Queen Margaret gained the upper hand politically. She united Denmark, Sweden and Norway and formed the Kalmar Union. The Hanseatic League was forced to cooperate with her, foreshadowing its eventual decline.

At the same time, the Victual Brothers were impartially raiding everyone's shipping. Their famous battle cry was "God's friends and the whole world's enemies". Queen Margaret and King Albert of Sweden conceded Gotland to the allied Teutonic Order as a pledge (similar to a fiefdom). An invasion army under Konrad von Jungingen, the Grand Master of the Order, conquered the island in 1398, destroying Visby and driving the Victual Brothers out of Gotland.

After the Victual Brothers' defeat and expulsion from Gotland in 1398, the Hanseatic League tried repeatedly but unsuccessfully to completely control the Baltic Sea. Many Victual Brothers still remained at sea. When they lost their influence in the Gulf of Bothnia, the Gulf of Finland and Gotland, they operated from the Schlei, the mouth of the river Ems and other locations in Friesland. The successors to the Victual Brothers gave themselves the name Likedeelers ("equal sharers"): they shared with the poor coastal population. They expanded their activities into the North Sea and along the Atlantic coastline, raiding Brabant and France and striking as far south as Spain.

Their most famous leader was Captain Klaus Störtebeker. He allegedly got his name because he could swallow four litres of beer without taking the beaker from his mouth. However, it might simply be a family name from Wismar. The Low German word Störtebeker means "Down the beakerful". In 1401 the Hamburg warship Bunte Kuh, leading a small fleet under Commander Simon of Utrecht, caught up with Störtebeker's forces near Heligoland. After three days' running battle, Störtebeker and his crew were finally overpowered and trapped by means of a trick.

However this was not the end of piracy and coastal raiding by the Likedeelers. In 1429, some 28 years after the execution of Störtebeker, other members of the Victual Brothers attacked and plundered the city of Bergen in Norway, eventually burning it to the ground. Until about 1440, maritime trade in both the North Sea and the Baltic Sea was seriously in danger of attack by the Likedeelers.